Artificial foot

ABSTRACT

An artificial foot including an inelastic core occupying substantially the full height of the middle portion of the foot and the entire width of the foot and having a pair of elongated flat elastic leaf springs projecting forward and rearward from the middle portion of the core, so that the leaf springs will flex relative to the core under the weight of the wearer when walking, the free ends of both springs being separated from the respective portions of the core by resilient materials.

United States Patent [61 Orange Oct. 23, 1973 1 ARTIFICIAL FOOT [76] Inventor: jdhri IQ. Oi ange, R0u te NEIL 3 Russellville, Ky. 42276 [21] Appl. No.2 295,196

[52] US. Cl. 3/7 [51'] Int. Cl. A61i 1/08 [58] Field of Search 3/6-8, 3/23, 33

[56] References Cited UNITED STATES PATENTS 546,405 9/1895 Marks et al 3/7 1,219,374 3/1917 Carrico 3/7 3,098,239 7/1963 Nader 3/7 3,484,871 12/1969 Orange 3/7 FOREIGN PATENTS OR APPLICATIONS 354,246 6/1922 Germany 3/7 -Primary Examiner-Richard A. Gaudet Assistant Examiner-Ronald L. Frinlcs Attorney-Harrington A. Lackey [57] ABSTRACT An artificial foot including an inelastic core occupying substantially the full height of the middle portion of the foot and the entire width of the foot and having a pair of elongated flat elastic leaf springs projecting forward and rearward from the middle portion of the core, so that the leaf springs will flex relative to the core under the weight of the wearer when walking, the free ends of both springs being separated from the re- 1 spective portions of the core by resilient materials.

2 Claims, 2 Drawing Figures ARTIFICIAL FOOT BACKGROUND OF THE INVENTION This invention relates to an artificial foot, and more particularly to an artificial foot adapted to be fixed to a prosthetic ankle element.

This invention is an improvement over the artificial foot disclosed in applicants US. Pat. No. 3,484,871 issued Dec. 23, 1969.

In the previous Orange patent, an inelastic core having a forward projecting arch portion was provided with a metal elastic leaf spring fixed to the bottom of the, core and projecting forward beyond the convex arch. The leaf spring was protected with a resilient pad and a layer of webbing.

However, in the previous Orange patent, the core pad and webbing were of the same width as the leaf spring, which in turn was substantially narrower than the width of the foot, occupying only about one-third of the total width of the foot. Moreover, in the previous Orange patent, the entire heel portion throughout its height was occupied-by resilient material. No portion- SUMMARY OF THE INVENTION It is therefore an object of this invention to provide an artificial foot which is an improvement over the artificial foot disclosed in the previous Orange US. Pat. No. 3,484,871, and which is a decided improvement over other prior art artificial feet.

The artificial foot made in accordance with this invention includes an inelastic, preferably wood, core having a front portion and a heel portion extending the full width of the foot and merging in a middle portion extending substantially the full height of the foot. The heel'portion tapers rearward terminating at the rear end of the foot, while the 'front portion tapers or converges forward to form a rounded extremity spaced forward of the ball of the foot.

A first or rear leaf spring has its front end secured to the bottom of the middle portion of the core and projects rearward diverging from the bottom surface of the core and providing a space occupied by a wedgeshaped resilient member. A second or front elastic metal leaf spring has its rear end fixed to the bottom of the middle portion of the core in the center of and in longitudinal alignment with the rear spring and projects forward, also diverging away from the bottom surface of the front core portion and extending substantially beyond the rounded front. extremity of the core. The space between the front spring and the bottom surface of the front portion of the core is occupied by a resilient pad sandwiched between the spring and an upper webbing member.

The remaining spaces of the foot are occupied by a hard rubber composition to fill out and complete the shape of the artificial foot.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional elevation taken substantially along the line l-1 of FIG. 2;. and

FIG. 2 is a section taken along the line 22 of. FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in more detail, the artificial foot 10 includes a solid, inelastic core 11, preferably made of wood, having a rear or heel portion 12, a middle or intermediate portion 13, and a front portion 14. The width of the entire core 11, including all three portions 12, 13 and 14, is equal to the width of the foot at the corresponding transverse cross-sections, as illustrated in FIG. 2.

The front of the heel portion 12 and the rear of the front portion 14 merge to form the short middle core portion 13, which extends substantially the full height of the foot.

The heel portion 12 extends from the middle portion 13 rearward to terminate at the rear of the foot. The top surface 16 of the heel portion 12 is flat and substantially horizontal. The bottom surface 17 of the heel portion 12 inclines rearward from the bottom of the intermediate portion 13 in a plane which terminates at the rear end 15 of the foot 10. Fixed to the bottom surface 18 of the intermediate portion 13 is the front end of a first or heel spring 20, by securing means such as screw 21. The heel spring 20 is a flat, elastic, metal leaf spring of unifonn width and thickness, which projects rearward, diverging from the bottom surface 17 of the heel portion 12 and terminating in the end 22 a short distance from the rear end of the foot 10.

Inserted between the heel spring 20 and the bottom surface 17 of the heel portion 12 to fill the space therebetween is a wedge-member 24 of a soft, resilient material, such as soft rubber. The wedge-member 24 provides acushion between the core 11 and the heel spring 20 to absorb the shockbetwe'en these two members as the heel of the wearer is placed down upon the surface upon which he is walking. The wedge-member 24 not only absorbs the force of the wearers weight exerted upon his heel, but also yields to the fiexure of the heel spring 20 as it yields under the heel thrust.

The front core portion 14 has a top surface 25 which slopes forward and downward to conform to the general contour of the corresponding upper portion of the foot 10. The bottom surface 26 of the front core portion 14 gradually converges upward from the bottom surface 18 of the intermediate portion 13 until it converges with the top surface 25 in a rounded front extremity 27 at a point in front of a vertical line 28 extending substantially through the ball of the foot. The bottom surface 26 may be flat in part and curved in part, or gradually curved, but preferably curves in its forward portion to form the rounded front extremity 27.

A front fiat elastic leaf spring 30 is mounted at its rear end by ascrew 31 to the bottom surface 18 of the intermediate core portion 13. The front leaf spring 30 is preferably of the same width as the heel spring 20 and secured in coextensive alignment with and substantially abutting end-to-end with the heel spring 20. The front leaf spring 30 projects forward substantially along, below, and in the same-direction as the bottom surface 26 of the front core portion 14. The front end of the spring 30 terminates in a front end or edge 32 in a position spaced slightly rearward of the toe of the foot 10, but substantially forward and below the front extremity 27 of the core 11.

The strength and gauge of the front leaf spring 30 is such that when the foot is flexed, such as when the weight of the wearer shifts forward over the ball of the foot for walking, the spring 30 will flex about the ball of the foot and will curve toward the rounded extremity 27. The bottom surface 26 of the front core portion 14 provides a limit to the upward flexing of the spring 30.

The strength and gauge of the springs 20 and 30 are also such that they will withstand numerous flexures, and maintain their elastic properties to restore the heel and toe of the foot to their original positions, as disclosed in FIG. 1, after each walking step when the weight of the wearer is released from the corresponding portion of the foot 10. The strength and gauge of the springs and 30 may be identical or the heel spring 20 may be stiffer, thicker or less elastic than front spring 30. Furthermore, the strength of the spring 30, as well as its cooperation with the bottom core surface 26, is such that the toe portion of the foot 10 will not bend excessively and give way, causing the knee of the wearer to buckle."

A soft resilient pad 34, made of a material such as the soft rubber in wedge member 24, is positioned between the spring 30 and bottom core surface 26, so as to extend fore and aft of the front rounded extremity 27. The rear end of the pad 34 is positioned slightly forward of the mounting screw 31 where the space begins to open between the bottom surface 26 and the front spring 30. The front end of the pad 34 projects substantially forward of the front extremity 27, but not so far as the front end 32 of the spring 30.

Located on top of the pad 34 and extending coextensively widthwise and lengthwise with the pad 34 is a webbing member 35 made of nylon webbing, belting or other comparable material. The front and rear extremities of the webbing member 35 are co-terminous with the front and rear ends of the pad 34. The rear end portion of the webbing 35 may be secured by adhesives or other means to the bottom surface 26 of the front core portion 14.

The pad 34 provides a cushion between the core 11 and the front leaf spring 30 to absorb the shock between these two members during the flexure of the front or toe portion of the foot 10. The webbing member 35 not only holds the soft rubber pad 34 in place, but also provides a protective cover for the pad 34 against wear against the bottom surface 26 of the front core portion 14, and against the rounded front extremity 27.

The remainder of the foot 10 includes a resilient cover portion 37, preferably of hard rubber, that is harder than the soft rubber of wedge member 24 and pad 34, which fills those spaces not occupied by the core 11, springs 20 and 30, wedge member 24, pad 34 and webbing member 35, to round out or complete the shape of the foot 10. The cover portion 37 is disclosed as completing the front portion of the foot 10 in front of the extremity 27, filling in the space between the webbing member 35 and the bottom surface 26, and optionally covering the top surface 25. Formed either as an integral part of the cover portion 37, or formed as a separate piece to be secured to the bottom of the cover portion 37, and made of the same hard rubber material is a spring rim 38. The spring rim 38 merely fills out the spaces around the margins of the leaf springs 20 and 30, or in other words provides a recess in the bottom of the foot portion for receiving the springs 20 and 30, since the width of the springs 20 and 30 is not as great as the width of the foot.

The bottom of the foot 10 is covered by a hard rubber sole 40, which is fitted flush against the bottom surfaces of the rim meber 38, and the bottom surfaces of both springs 20 and 30. The sole 40 may be secured in place by any conventional adhesive.

The hard rubber foot cover portion 37, as well as the solde 40, and the rim 38, define the exterior shape of the foot, are of the same composition, and are more or less conventional in prosthetic footwear.

A vertical bore 41 extends through the heel core portion 12 and communicates with a larger cylindrical cavity 42 extending through the sole 40, the heel spring 20 and the wedge member 24. The bore 41 and the cavity 42 are adapted to receive conventional securing means, such as an elongated bolt, not shown, to fixedly secure the core 11, and thereby the foot 10, rigidly to a prosthetic ankle element, not shown.

FIG. 1 discloses the foot 10 in its normal, inoperative, or standing position, where the weight of the wearer extends vertically through his legs, and all of the weight through one leg is substantially supported by the core 11. When the foot 10 acts as the trailing foot in the walking cycle, the weight of the wearer is transmitted gradually forward along the front core portion 14, so that the heel portion of the foot 10 is raised and the core 11 rocks upon the upwardly converging curved portion of the bottom surface 26, bearing down upon the web member 35, rubber pad 37, front spring 30 and the foot ball portion of the sole 40. As the core 11 is raised, the rear portion of the spring 30 is carried with it, causing the spring 30 to flex in the ball area of the foot. The front spring 30 is strong enough and has sufficient elastic properties to prevent excessive bending even under the weight of a heavy wearer, and yet will permit a normal foot action. The spring 30 is also reinforced by the bottom surface 26 of the core portion 14, which also provides a limit to the flexing movement of the front toe portion of the foot 10, so that the foot 10 will not give way and cause the leg of the wearer to buckle. As the weight of the wearer moves over the ball area of the trailing foot, the trailing knee is substantially in vertical alignment with the ball area, that is in alignment with the line 28. The heel of the leading foot engages the ground to begin receiving the weight of the walker. Accordingly, the heel spring 20 is flexed as a cantilever about the screw mounting 21 to compress the soft rubber wedge member 24. The wedge member 24 also absorbs any shock from any abrupt striking of the heel portion of the foot 10 upon the walking surface.

The location of the front extremity 27 of the front core 14 in front of the ball area of the foot therefore becomes important to prevent the knee from buckling" and to prevent the leaf spring 30 from breaking.

As the trailing foot 10 is lifted, the elastic properties of the spring 30 will thrust or project the trailing foot, and thus the walker, forward, and will also restore the entire foot to its original position disclosed in FIG. 1. Moreover, as the weight of the wearer gradually passes longitudinally forward over the foot 10, the pressure is gradually reduced upon the wedge member 24 and the heel spring 20, permitting these elastic members to be restored to their original positions disclosed in FIG. 1, and also to provide a slight thrust to the heel of the wearer as weight is removed from the heel portion to carry him forward as his foot begins compressing the front leaf spring 30. In other words, both heel and front springs 20 and 30 provide a little "spring to the step of the wearer.

Another important feature of the invention is the extension of the width of the core 11 to the full width of the foot, which provides substantial additional lateral stability to the foot during the walking cycle. Although it is not necessary to extend the width of the leaf springs 20 and 30 to the full width of the foot 10, nevertheless the webbing member 35 and the pads 24 and 34 should have the same full width of the foot 10 in order to uniformly absorb the pressures exerted by the bottom surfaces 17 and 26 of the heel and front core portions 12 and 14 during the walking cycle. The full width of the webbing 35 is then of course needed to protect the top of the pad 34 from compression by the bottom surface 26 of the front core portion 14.

What is claimed is:

1. An artificial foot comprising:

a. an inelastic core having a heel portion and a front portion extending the full width of the foot,

b. the front of said heel portion and the rear of said front portion merging in a middle portion extending substantially the full height of said foot,

c. said heel portion extending from said middle portion to the rear end of the foot,

d. said heel portion having a top surface extending the length of said heel portion,

e. said heel portion having a bottom surface inclined rearward from the bottom of said middle portion, and terminating at the rear of the foot,

f. said front core portion having top and bottom surfaces converging to form a front rounded extremity spaced above and forward of the ball of the foot,

g. the bottom surface of said front core portion converging upward into said rounded extremity,

h. a first elongated, flat, metal, leaf spring having a front end and a rear end,

i. means securing the front end of said first leaf spring to the bottom of said middle core portion so that the rear end of said first spring projects rearwardly spaced below the bottom surface of said heel portion and terminates a short distance from the rear of the foot,

j. a wedge-shaped resilient member substantially the width of the foot and secured between the bottom surface of said heel portion and said first leaf spring and terminating at the rear of the foot,

k. a second elongated, flat, metal, leaf spring having a front end and a rear end, and of sufficient strength and elasticity to flex a predetermined distance under the weight of the wearer of the foot when walking, and to be restored to its original position when the weight is relieved,

l. securing means fixing the rear end of said second leaf spring flush against the bottom surface of said middle core portion and adjacent and in line with the front end of said first leaf spring, so that said second leaf spring projects forward below the bottom surface of the front portion, and the front end of said second spring is spaced forward of said front extremity,

m. a soft, resilient pad mounted on top of said second leaf spring, spanning the width of the foot, and extending from a point slightly forward of the rear end of said second leaf spring forward substantially beyond said front extremity,

' n. a flexible webbing member mounted upon said resilient pad, said webbing member having a rear end portion fixed to the bottom surface of said front core portion, and being substantially coextensive in width and length with said pad,

0. an upper foot portion of resilient material substantially harder than said pad and occupying the space in front of said rounded extremity, and the space between said front core portion and the top of said webbing member,

p. a sole member of resilient material of the same hardness as said upper foot portion covering the bottoms of said leaf springs and secured to said upper foot portion, and

q. a vertical bore extending through said heel portion, said wedge member, said first leaf spring and said sole member to receive an elongated securing means for securing the foot to a prosthetic ankle segment.

2. The invention according to claim 1 in which said first leaf spring is thicker than said second leaf spring. 

1. An artificial foot comprising: a. an inelastic core having a heel portion and a front portion extending the full width of the foot, b. the front of said heel portion and the rear of said front portion merging in a middle portion extending substantially the full height of said foot, c. said heel portion extending from said middle portion to the rear end of the foot, d. said heel portion having a top surface extending the length of said heel portion, e. said heel portion having a bottom surface inclined rearward from the bottom of said middle portion, and terminating at the rear of the foot, f. said front core portion having top and bottom surfaces converging to form a front rounded extremity spaced above and forwaRd of the ball of the foot, g. the bottom surface of said front core portion converging upward into said rounded extremity, h. a first elongated, flat, metal, leaf spring having a front end and a rear end, i. means securing the front end of said first leaf spring to the bottom of said middle core portion so that the rear end of said first spring projects rearwardly spaced below the bottom surface of said heel portion and terminates a short distance from the rear of the foot, j. a wedge-shaped resilient member substantially the width of the foot and secured between the bottom surface of said heel portion and said first leaf spring and terminating at the rear of the foot, k. a second elongated, flat, metal, leaf spring having a front end and a rear end, and of sufficient strength and elasticity to flex a predetermined distance under the weight of the wearer of the foot when walking, and to be restored to its original position when the weight is relieved, l. securing means fixing the rear end of said second leaf spring flush against the bottom surface of said middle core portion and adjacent and in line with the front end of said first leaf spring, so that said second leaf spring projects forward below the bottom surface of the front portion, and the front end of said second spring is spaced forward of said front extremity, m. a soft, resilient pad mounted on top of said second leaf spring, spanning the width of the foot, and extending from a point slightly forward of the rear end of said second leaf spring forward substantially beyond said front extremity, n. a flexible webbing member mounted upon said resilient pad, said webbing member having a rear end portion fixed to the bottom surface of said front core portion, and being substantially coextensive in width and length with said pad, o. an upper foot portion of resilient material substantially harder than said pad and occupying the space in front of said rounded extremity, and the space between said front core portion and the top of said webbing member, p. a sole member of resilient material of the same hardness as said upper foot portion covering the bottoms of said leaf springs and secured to said upper foot portion, and q. a vertical bore extending through said heel portion, said wedge member, said first leaf spring and said sole member to receive an elongated securing means for securing the foot to a prosthetic ankle segment.
 2. The invention according to claim 1 in which said first leaf spring is thicker than said second leaf spring. 